Not Applicable
Not Applicable
The present invention relates to electro-mechanical actuators, and more particularly, to devices for providing precisely controlled actuation of spray pump mechanisms.
The US Food and Drug Administration (FDA) strongly recommends automated actuation of nasal spray devices subject to in-vitro bioequivalence testing to decrease variability in drug delivery due to operator factors (including removal of potential analyst bias in actuation) and increase the sensitivity for detecting potential differences between drug products. The FDA further recommends that an automated actuation system has settings or controls for actuation force, length of stroke, actuation velocity, hold time, return time, delay time between successive actuations, and actuation number. Selection of appropriate settings should be relevant to proper usage of the nasal aerosol or nasal spray by the trained patient, and should be documented based on exploratory studies in which actuation force, actuation time, and other relevant parameters are varied. One such study includes xe2x80x9cGuidance for Industry: Bioavailability and Bioequivalence Studies for Nasal Aerosols and Nasal Sprays for Local Action,xe2x80x9d by Wallace P. Adams, U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER), June 1999.
Thorough characterization of the spray pump""s performance in terms of its emitted spray pattern, plume geometry and/or droplet size distribution are known to be affected by the means in which the spray pump is actuated. For example, slow actuation will likely cause poor atomization, producing a stream-like flow. Fast actuation will likely cause too fine a spray to be produced, leading to poor absorption in the nasal mucosa and unwanted inhalation and deposition of the droplets in the throat and lungs.
From a mechanical perspective, over-actuation (forcing the spray pump assembly beyond its intended stopping point) of the spray pump device must be avoided. If the spray pump mechanism is over-actuated, permanent deformations can occur to the delicate pump orifice, swirl chambers and/or closure mechanisms, all of which can manifest themselves in higher than expected variability in the pump""s spray performance and flow characteristics. Further, rigidly holding the nozzle of the spray pump in place during actuation is vital to ensure that the spray develops properly and exits the nozzle normally so that measurements of spray pattern, plume geometry and droplet size distribution are not artificially biased due to unwanted movement of the nozzle.
The Innova Systems (Pernsauken, N.J.) Nasal Spray Pump Actuators (NSP and eNSP) are prior art automated nasal spray actuators. Both models use the same operating principle: a pneumatic cylinder connected to a solid plate (contact plate) is used to compress the spray pump against a spring loaded holding plate and clip mechanism. Typically, these actuators are connected to a compressed air source and a computer interface to allow a user to set the actuation force, contact force, holding time, and dose time for the actuation event. In operation, these actuators adjust an air pressure regulator so that the pneumatic cylinder will first apply the prescribed contact force to the bottom side of the spray pump. Presumably, this application of the contact force is done to minimize the time delay in producing the spray and/or to prevent the compression plate from striking the spray pump with a dynamic load, which could damage the pump due to the high dynamic forces achievable in the system. Next, the pressure regulator is adjusted again so that the pneumatic cylinder applies the prescribed actuation force (typically higher than the contact force). This action compresses the spray pump at a rate determined by the pneumatic efficiency of the system and the mechanical spring resistance of the spray pump and fluid combination. The compression rate cannot be controlled. As a result, once the pressure regulator is set, the contact plate will move at a rate determined by the system, not the user.
Experience with using these actuators has shown the following difficulties and shortcomings:
1. Lack of position and velocity controls leads to uncontrolled, xe2x80x9cair hammerxe2x80x9dxe2x80x94like performance with substantial spray pump over-actuation. This phenomenon has led to measurable degradation in spray pump performance over time and larger than expected variations in delivered dosage content. These problems are likely due to progressive deterioration in the moving pump components due to over-actuation.
2. Lack of a nozzle holding mechanism leads to unwanted movements of the nozzle during actuation. This causes artificial distortions and substantial variability to appear in the associated spray pattern and plume geometry test data.
3. Difficulties associated with pneumatic control lead to oscillating contact force application and this leads to pre-spray droplets forming on the nozzle tip and measurable variability in spray pattern, plume geometry, and droplet size distribution data.
4. Reliance on variable quality, laboratory compressed air sources leads to inconsistent actuation performance and potential safety issues.
5. Uncertain actuation event-time triggering causes difficulty in acquiring time critical spray data such as spray pattern and plume geometry.
6. Uncertain applied force measurements do not give a user confidence that the actuator is applying the desired force to the spray pump.
7. Absence of recordable applied force and/or position/velocity data make it difficult to chronicle the actuation event history.
In one aspect, a system for actuating a spray pump assembly including a reservoir component and a pump/nozzle component comprises a reference platform, a motor component, a drive transmission component, a spray pump holder component, a force coupler, a force transducer, and a system controller. The reference platform provides a foundation upon which the components of the system are mounted. The motor component is fixedly attached to the reference platform, receives a power input and a control input, and produces a rotary drive output therefrom. The drive transmission component is fixedly attached to the reference platform, receives the rotary drive output and produces a linear drive output therefrom. The spray pump holder component is removably attached to the reference platform, and removably secures the spray pump assembly. The force coupler couples the linear drive output to the spray pump mechanism, so as to apply a force to the spray pump mechanism. The force transducer produces a force signal proportional to the force applied to the spray pump mechanism. The system controller receives a set of test inputs including (i) the force signal, (ii) one or more feedback signals from the motor component, and (iii) user input corresponding to spray pump test parameters. The system controller provides the control input to the motor component as a predetermined function of the set of test inputs. The system is operative to actuate the spray pump mechanism according to an actuation profile defined by the set of test inputs.
In one embodiment, the motor component includes a servomotor. In another embodiment, the servomotor includes a motor controller for receiving and processing the control input and for providing the one or more feedback signals, and for storing the actuation profile. The servomotor includes an encoder for monitoring the angular position of the rotary drive output and for producing an angular position signal corresponding to the angular position of the rotary drive output. The servomotor further includes a driver for receiving the actuation profile from the motor controller and the power input, and for producing a drive signal therefrom. The servomotor also includes an electric rotary motor for receiving the drive signal and for producing the rotary drive output therefrom.
In another embodiment, the motor component includes any one of a variety of stepper motors known in the art.
In another embodiment, the actuation profile includes a quiescent position of the spray pump mechanism.
In another embodiment, the actuation profile includes a fully actuated position of the spray pump assembly.
In another embodiment, the actuation profile includes a velocity profile from a quiescent position of the spray pump assembly to a fully actuated position of the spray pump mechanism.
In another embodiment, the velocity profile includes velocity with respect to time.
In another embodiment, the actuation profile includes a force profile from a quiescent position of the spray pump mechanism to a fully actuated position of the spray pump mechanism.
In another embodiment, the force profile includes force with respect to time.
In another embodiment, the actuation profile includes a hold time parameter corresponding to an amount of time the spray pump assembly is held in a fully actuated position.
In another embodiment, the drive transmission component includes at least one linear screw-rail assembly.
In another embodiment, the at least one linear screw-rail assembly includes an anti-backlash linear screw-rail assembly.
In another embodiment, the at least one linear screw-rail assembly includes a low friction coating on at least a screw component within the linear screw-rail assembly.
In another embodiment, the low friction coating includes a Teflon-based material.
In another embodiment, the at least one linear screw-rail assembly includes ball bearing supports for supporting a screw component within the linear screw-rail assembly.
Another embodiment further includes a first pulley fixedly attached to the rotary drive output, a second pulley fixedly attached to a screw component within the linear screw-rail assembly, and a drive belt for coupling the first pulley to the second pulley.
In another embodiment, the first pulley and the second pulley each include a plurality of teeth, and the drive belt includes a plurality of ribs, such that in operation the teeth on the first pulley and the teeth on the second pulley mesh with the ribs on the drive belt.
In another embodiment, the rotary drive output is directly coupled to the drive transmission component.
In another embodiment, the spray pump holder component removably secures the pump/nozzle component, and the coupler couples the linear drive output to the reservoir component.
In another embodiment, the spray pump holder component removably secures the reservoir component, and the coupler couples the linear drive output to the pump/nozzle component.
In another embodiment, the force transducer is disposed between the spray pump assembly and linear drive output.
In another embodiment, the force transducer is disposed between the spray pump assembly and the spray pump holder component.
In another embodiment, the force transducer is disposed between the spray pump holder and the reference platform.
In another embodiment, the system controller includes a digital acquisition assembly for sampling an angular position signal that characterizes the angular position of the rotary drive output, so as to generate one or more digital samples corresponding to the angular position signal. The system controller further includes a computer system that receives the set of test inputs and the one or more digital samples, generates the actuation profile and provides the actuation profile to the motor component. The computer system also receives the one or more feedback signals from the motor component and recording one or more physical parameters of the spray pump assembly during actuation.
In another embodiment, the one or more physical parameters of the spray pump assembly includes a position versus time profile that describes the position of the nozzle pump component with respect to the reservoir component as a function of time.
In another embodiment, the one or more physical parameters of the spray pump assembly includes a force versus time profile that describes force applied to the nozzle pump component with respect to the reservoir component as a function of time.
In another embodiment, the computer system performs a calibration procedure, calculates one or more compensation values, and uses the compensation values to modify the one or more physical parameters.
In another embodiment, the computer system performs a calibration procedure, calculates one or more compensation values, and uses the compensation values to modify the control input to the motor component.
In another embodiment, the system controller generates an actuation profile representative of a human hand actuating the spray pump assembly.
In another aspect, a method of actuating a spray pump via an actuator system comprises removably securing the spray pump assembly to a spray pump holder component. The method further comprises determining (i) a quiescent position of the spray pump, and (ii) a fully actuated position of the spray pump assembly. The method further comprises generating an actuation profile as a predetermined function of the quiescent position, the fully actuated position, and user input corresponding to spray pump test parameters. The method also comprises actuating the spray pump according to the actuation profile. The actuator system includes a rotary motor driving a linear screw-rail assembly, thereby applying a force to the spray pump assembly.
In another embodiment, the step of determining the quiescent position of the spray pump further includes measuring an amount of force applied to the spray pump assembly, and advancing the linear screw rail assembly until the amount of force applied to the spray pump assembly exceeds a first predetermined value. The step of determining the quiescent position of the spray pump assembly also includes recording a position of the linear screw rail assembly when the amount of force applied to the spray pump assembly exceeds the first predetermined value.
In another embodiment, the step of determining the fully actuated position of the spray pump assembly further includes continuing to advance the linear screw rail assembly until the amount of force applied to the spray pump assembly exceeds a second predetermined value. The step of determining the fully actuated position of the spray pump assembly also includes recording a position of the linear screw rail assembly when the amount of force applied to the spray pump assembly exceeds the second predetermined value.
In another aspect, a spray pump holder for securing a spray pump assembly includes a clamp having an aperture disposed about a central axis, and a plurality of fingers disposed about the perimeter of the aperture and extending out from the clamp parallel to the central axis. The spray pump holder also includes a compression member removably attached to the clamp. The pump/nozzle component is inserted into the aperture along the central axis, and the compression member, when attached to the clamp, compresses the plurality of fingers against the pump/nozzle component so as to secure the pump/nozzle component to the clamp.
In another embodiment, the clamp consists of a low friction material. In one embodiment, the low friction material is Teflon.
In another embodiment, the compression member is constructed and arranged so as to variably compress the plurality of fingers against the pump/nozzle component.
In another embodiment, the clamp and the compression member include mating threads, such that the compression member screws into the clamp and drives the fingers toward the central axis. In one embodiment, the compression member consists of anodized aluminum.
Another embodiment of the spray pump holder further includes an annular insert disposed about the central axis, between the fingers and the central axis. The pump/nozzle component is inserted through the annular insert and the fingers compress the annular insert against the pump/nozzle component. In another embodiment, each of the fingers is characterized by a triangular cross section in a plane perpendicular to the central axis.
In another embodiment, the clamp is characterized by a substantially square body, disposed within a plane that is perpendicular to the central axis. In another embodiment, opposite sides of the square body slide into, or otherwise engage, corresponding grooves in a reference platform.
In another aspect, a spray pump holder for securing a spray pump assembly comprises a bracket for supporting the spray pump assembly, and at least one securing strap for removably securing the spray pump assembly against the bracket.
In another embodiment, the bracket includes a first cradle member having a first engaging surface for retaining a first surface of the reservoir component, and a second cradle member having a second engaging surface for retaining a second surface of the reservoir component.
In another embodiment, the first engaging surface is substantially orthogonal to the second engaging surface.
In another embodiment, the first engaging surface includes a V-shaped surface, so that the first engaging surface contacts a reservoir component having an arcuate exterior surface at two locations.
In another embodiment, the second engaging surface includes a V-shaped surface, so that the second engaging surface contacts a reservoir component having an arcuate exterior surface at two locations.
In another embodiment, the bracket further includes an aperture, disposed between the first cradle member and the second cradle member, for accommodating a heel portion of the spray pump assembly.
Another embodiment of the spray pump holder further includes a first securing strap and a second securing strap. The first securing strap secures the spray pump assembly against the first cradle member, and the second securing strap secures the heel portion of the spray pump assembly into the aperture and against the second cradle member. In one embodiment of the spray pump holder, a first end of the at least one securing strap is fixedly attached to a first anchor on the bracket, and a second end of the at least one securing strap is removably attached to a second anchor on the bracket.
In another embodiment, the second end of the at least one securing strap loops around the second anchor removably attaches to a distal portion of the securing strap.
In another aspect, a spray pump holder for securing a spray pump assembly comprises a base including a body member, and a housing member having a stop tab. The spray pump holder further includes a clamping assembly including a first lever and a second lever pivotally attached at a pivot point about a pivot axle. The spray pump holder also includes a spring attached to the first lever and the second lever so as to force together a first end of the first lever and a first end of the second lever. The stop tab provides a platform or buttress, against which a pump/nozzle component of a spray pump assembly presses, and the pump/nozzle component is secured between the first end of the first lever and a first end of the second lever.
In another embodiment, the body member is characterized by a square body, and opposite sides of the square body slide into corresponding grooves in a reference platform.